JP2012199571A - Polycrystalline solar cell panel and manufacturing method thereof - Google Patents

Abstract

A low-cost polycrystalline silicon solar cell is provided by providing a dopant-containing silicon ingot with high material efficiency.
A step A for preparing a silicon target containing a P-type or N-type dopant and a silicon target containing a P-type or N-type dopant are used to form a P-type or N-type amorphous silicon on the substrate surface. A process B for forming a film by sputtering, a process C for forming a P-type or N-type polycrystalline silicon film by scanning and melting a P-type or N-type amorphous silicon film and then recrystallizing it, and a process C The PN junction is formed by exposing the P-type polycrystalline silicon film formed in step 1 to the plasma with the gas containing the N-type dopant, or the P-type dopant is added to the N-type polycrystalline silicon film formed in Step C. A method for manufacturing a polycrystalline solar cell panel, comprising: a step D of forming a PN junction by exposure to plasma with a gas including the same.
[Selection] Figure 5

Description

  The present invention relates to a polycrystalline solar cell panel and a method for manufacturing the same.

  Silicon crystal solar cells can be broadly classified into single crystal solar cells and polycrystalline solar cells. In general, a crystalline solar cell has a thickness of 200 μm by cutting an n-type or p-type doped silicon ingot 30 with a wire 31 or using a dicing technique, as shown in FIG. The sliced ingot is used as a silicon wafer that becomes the main body of the solar cell (see Patent Document 1). The silicon ingot 30 may be a single crystal silicon ingot produced by the Czochralski method or the like, or a polycrystalline silicon ingot that is solidified using a molten silicon mold called a cast method.

  In addition, as a method for producing a polycrystalline silicon film of a polycrystalline solar cell, a method is also known in which silicon particles deposited on a support substrate are melted to be polycrystallized (see Patent Document 2). FIG. 9 shows a polycrystalline silicon film forming apparatus. Silicon particles 42 (20 nm or less) generated by applying an arc discharge 41 to the silicon anode 40 are deposited on the support substrate 45 through the transport tube 44 on the argon gas 43; the silicon particles 42 deposited on the support substrate 45 are High temperature plasma 46 is irradiated and melted; annealing is performed with a halogen lamp 47 to form a polycrystalline silicon plate; in the separation chamber 48, the support substrate 45 and the polycrystalline silicon film 49 are separated.

  Further, a method of crystallizing amorphous silicon deposited on a glass substrate by catalytic chemical vapor deposition (Cat-CVD) with a high energy beam (flash lamp) has been studied (Patent Document 3 and Non-Patent Document). 1). According to this document, after forming Cr as an electrode on a 20 mm square quartz substrate, 3 μm of amorphous silicon is deposited by the Cat-CVD method, and is crystallized by performing a treatment for 5 ms with a flash lamp.

JP 2000-263545 A JP-A-6-268242 JP 2008-53407 A

Keisuke Ohira et al. "In-plane uniform crystallization of amorphous silicon thin film by flash lamp annealing" 54th Annual Meeting of Applied Physics Society (Spring 2007) [Optical Technology Information Magazine "Light Edge" No.29 (issued in August 2007) ]

  The polycrystalline silicon solar cell includes a polycrystalline silicon film having a PN junction. In order to form a PN junction in a polycrystalline silicon film, 1) a dopant-containing material (generally glass) is deposited on the polycrystalline silicon film, and the dopant is thermally diffused (the dopant-containing material is removed by wet processing). 2) A dopant is implanted by placing a polycrystalline silicon film in a dopant-containing gas atmosphere.

  In these PN junction formation methods, the number of processes increases, the processing time increases, the use of a highly dangerous gas is required, the control of the doping amount and the control of the dopant implantation depth are difficult, etc. To do. Accordingly, a first object of the present invention is to provide a low-cost polycrystalline silicon solar cell by simply forming a polycrystalline silicon film having a PN junction.

  In the present invention, a polycrystalline silicon film having a PN junction is formed by polycrystallizing an amorphous silicon film formed by sputtering using a dopant-containing silicon ingot with plasma and forming a PN junction therewith. Thereby, a low-cost polycrystalline silicon solar cell is provided. Preferably, a polycrystalline silicon solar cell with lower cost is provided by providing a dopant-containing silicon ingot with high material efficiency.

The present invention relates to a method for producing a polycrystalline solar cell panel described below.
[1] Step A for preparing a silicon target containing a P-type or N-type dopant;
Using a silicon target containing the P-type or N-type dopant, a step B of forming a P-type or N-type amorphous silicon film on the substrate surface by sputtering;
A step C of forming a P-type or N-type polycrystalline silicon film by scanning and melting the P-type or N-type amorphous silicon film, followed by recrystallization;
A PN junction is formed by exposing the P-type polycrystalline silicon film formed in the step C to plasma with a gas containing an N-type dopant, or the N-type polycrystalline silicon film formed in the step C. And a step D of forming a PN junction by exposure to plasma with a gas containing a P-type dopant, and a method for manufacturing a polycrystalline solar cell panel.

[2] The method for manufacturing a polycrystalline solar cell panel according to [1], wherein the substrate includes any one of Al, Ag, Cu, Sn, Zn, In, and Fe.
[3] The method for producing a polycrystalline solar cell panel according to [1] or [2], wherein the plasma is atmospheric pressure plasma.
[4] The method for producing a polycrystalline solar cell panel according to any one of [1] to [3], wherein the scanning speed is 100 mm / second or more and 2000 mm / second or less.

[5] In the step C, after the P-type or N-type amorphous silicon film is melted by plasma irradiation, an inert gas is supplied to melt the P-type or N-type amorphous silicon film to be polycrystallized. The method for producing a polycrystalline solar cell panel according to any one of [1] to [4].
[6] The polycrystalline solar solar cell according to any one of [1] to [4], wherein in the step C, plasma irradiation is performed while extruding the generated plasma with a mixed gas obtained by mixing an inert gas with hydrogen gas. A method for manufacturing a battery panel.

  The present invention provides a solar cell panel including a polycrystalline silicon film. The polycrystalline silicon film in the solar cell panel of the present invention is formed by polycrystallizing an amorphous silicon film formed by sputtering using an impurity-containing silicon target using plasma. By this method, a polycrystalline silicon film having a PN junction can be easily formed. Therefore, this invention contributes to the cost reduction of a polycrystalline solar cell panel.

  Moreover, according to a preferred aspect of the present invention, the impurity-containing silicon target can be manufactured with high material efficiency. Therefore, according to the preferable aspect of this invention, it contributes further to the cost reduction of a polycrystalline solar cell panel.

It is a figure which shows the flow which obtains silicon powder from a silicon ingot, and obtains a silicon target. It is a figure which shows a mode that a silicon powder is irradiated with a plasma. A flow of sputtering an amorphous silicon film on a substrate is shown. An outline of a magnetron sputtering apparatus is shown. The flow which manufactures a solar cell panel is shown. The flow which manufactures a solar cell panel is shown. The flow which manufactures a solar cell panel is shown. It is a figure which shows a mode that a silicon ingot is sliced. It is a figure which shows the outline of the manufacturing apparatus of the conventional polycrystalline silicon film.

  The method for producing a polycrystalline solar cell panel according to the present invention includes a step of preparing a silicon target containing a dopant, a step of sputtering a dopant-containing amorphous silicon film on a substrate surface using the silicon target, and an amorphous silicon film. And irradiating plasma to a dopant-containing polycrystalline silicon film.

  The method for manufacturing a polycrystalline solar cell panel according to the present invention is as follows. 1) First mode in which the amorphous silicon film 2d is polycrystallized and then doped with a dopant to form a polycrystal silicon film having a PN junction (FIG. 5) and 2) an amorphous silicon film 2e is further formed on the amorphous silicon film 2d to form an amorphous laminated film, and the amorphous laminated film is polycrystallized to form a polycrystalline silicon film having a PN junction (see FIG. 6).

  The dopant-containing silicon target is obtained from a dopant-containing silicon ingot. The dopant-containing silicon target can also be obtained by slicing the dopant-containing silicon ingot; however, slicing the silicon ingot generates a large amount of cutting waste and is not material efficient. Therefore, the dopant-containing silicon target is preferably obtained by melting and recrystallizing a pulverized product of the dopant-containing silicon ingot.

  An outline of manufacturing a silicon target from a pulverized product of a dopant-containing silicon ingot is shown in FIG.

  First, a dopant-containing silicon ingot 1 is prepared (FIG. 1A). The dopant-containing silicon ingot may contain a P-type dopant or an N-type dopant. Examples of P-type dopants include boron, and examples of N-type dopants include phosphorus and arsenic. The dopant concentration in the silicon ingot is appropriately set according to the application.

  The dopant-containing silicon ingot only needs to satisfy the standard of solar great silicon. The silicon purity in the silicon ingot that meets the standard of solar great silicon is 99.99 wt%, preferably 99.999 wt%, more preferably 99.9999 wt%.

  The dopant-containing silicon ingot 1 is pulverized into silicon powder 2b (FIG. 1B). It is preferable that grinding | pulverization to a silicon powder is performed, without reducing the silicon purity of a dopant containing silicon ingot. Therefore, the pulverization of the dopant-containing silicon ingot 1 is preferably performed in a number of steps including the following two steps. By performing pulverization in combination of a number of steps, the ingot 1 can be pulverized in a shorter time than pulverizing to a desired particle size in one step.

  In the first step of pulverization, the dopant-containing silicon ingot 1 is made into silicon coarse powder 2a by ultra high pressure water cutting. The particle diameter of the silicon coarse powder 2a is about 3 mm or less, preferably 1 mm or less. Ultra high pressure water cutting is a method of cutting a substance using collision energy of ultra high pressure water. Ultra high pressure water may be water having a water pressure of about 300 MPa. The ultra high pressure water cutting can be performed using, for example, an ultra high pressure water cutting device manufactured by Sugino Machine. The water used at this time is preferably ultrapure water having a specific resistance of 18 MΩ · cm at a level used in a semiconductor process.

  In the second step of pulverization, the obtained silicon coarse powder 2a is made into silicon powder 2b by a wet atomization method, for example, a starburst device manufactured by Sugino Machine, a jet mill, ultrasonic destruction or shock wave destruction. The particle size of the silicon powder 2b is not less than 0.1 μm and not more than 100 μm, preferably not less than 0.3 μm and not more than 70 μm. Wet atomization is a process in which ultra-high pressure energy of 245 MPa is applied to the liquid in which the objects to be pulverized are dispersed in the flow path, once branched into the two flow paths, and the parts to be crushed are joined together at the part where they merge again. It is a wet atomization system that collides and pulverizes. Since wet atomization is a pulverization means that does not use a pulverization medium, as in the case of jet milling, ultrasonic destruction, and shock wave destruction, contamination of impurities can be suppressed.

  The particle diameter of the silicon powder 2b is set in consideration of the capacity of the pulverizing equipment, the production time in mass production, the time for melting the silicon powder 2b, and the like. When the particle size of the silicon powder 2b is 100 μm or less, the silicon powder 2b can be melted at a relatively low temperature. Since the general melting temperature of silicon is 1410 ° C., a large-scale furnace is required to melt silicon. However, when the particle size of the silicon powder is 100 μm or less, the melting temperature is lowered.

  Impurities that deteriorate the characteristics of the solar cell, such as Al, Fe, Cr, Ca, and K, are not mixed in the silicon powder 2b in the pulverization step (FIG. 1B). That is, it can be pulverized while maintaining the purity of the silicon ingot 1. Therefore, if the purity of the silicon ingot 1 is 99.99% or more (preferably 99.9999% or more), the purity of the obtained silicon powder is also 99.99% or more (preferably 99.9999% or more). Can do.

  On the other hand, when trying to pulverize the silicon ingot 1 using a pulverizer or a roller, impurities are mixed into the pulverized product, so that the silicon ingot 1 cannot be pulverized while maintaining the purity of the silicon ingot 1.

  Next, the obtained silicon powder 2b is placed on the substrate 10 (FIG. 1C). Instead of placing the silicon powder 2b on the substrate 10, it may be housed in a container. The material of the substrate 10 is not particularly limited, and may be copper (Cu), molybdenum (Mo), titanium (Ti), stainless steel (SUS), or the like.

In order to place the silicon powder 2b on the substrate 10, it is preferable to apply the dried silicon powder with a squeegee. The amount of silicon powder placed on the substrate 10 is preferably about 1.5 g / cm ² . Moreover, it is preferable that the amount of the silicon powder placed on the substrate 10 is such that the thickness of the obtained silicon target 2c is 5 to 15 mm.

  Next, the silicon powder 2b placed on the substrate 10 is irradiated with plasma to melt the silicon powder 2b, and further cooled and polycrystallized to obtain a silicon target 2c (FIG. 1C). The plasma may be vacuum plasma, but is preferably atmospheric pressure plasma because of the ease of processing and the convenience of the apparatus configuration.

  An outline of an atmospheric pressure plasma apparatus that can be used here is shown in FIG. As shown in FIG. 2, the atmospheric pressure plasma apparatus 50 includes a cathode 20 and an anode 21. A plasma injection port 22 is provided in the anode 21. When a DC voltage is applied between the cathode 20 and the anode 21, arc discharge is generated, so that plasma 23 is ejected from the plasma injection port 22 by flowing an inert gas (nitrogen gas or the like). Such an atmospheric pressure plasma apparatus is described in, for example, Japanese Patent Application Laid-Open No. 2008-53632.

  The substrate 10 on which the silicon powder 2b is mounted is mounted on a stage (not shown) movable to the XYZ axes of the atmospheric pressure plasma apparatus 50, and the surface of the substrate 10 is scanned from one end to the other with atmospheric pressure plasma. Heat treatment is performed. The temperature of the atmospheric pressure plasma is 10,000 ° C. or higher, but it is preferable to adjust the temperature at the tip of the plasma injection port 22 to be about 2000 ° C. The plasma injection port 22 is disposed at a distance of about 5 mm from the silicon powder 2 b of the base 10. The input power is 20 kW, and the plasma 23 is extruded with an inert gas and sprayed onto the substrate 10. The plasma 23 from the injection port 22 is irradiated to a 40 mm diameter region on the surface of the substrate 10. The silicon powder 2b in the region irradiated with the plasma 23 is melted.

  The temperature of the atmospheric pressure plasma 23 on the surface of the substrate 10 can be arbitrarily controlled by the power of the atmospheric pressure power source, the distance between the injection port 22 and the substrate 10, and the like. The melting condition of the silicon powder 2b is adjusted by appropriately controlling the temperature of the atmospheric pressure plasma 23 on the surface of the substrate 10.

  After the silicon powder 2b is melted, it is further polycrystallized by cooling with an inert gas (nitrogen gas or the like). Thereby, the silicon target 2 c is formed on the substrate 10. At this time, when the molten silicon powder 2b is rapidly cooled, it becomes polycrystalline silicon having a small crystal grain size.

  A trace amount of hydrogen gas may be mixed with an inert gas that extrudes plasma. By mixing a small amount of hydrogen, the oxide film formed on the surface of the silicon particles 2b can be removed, and the silicon target 2c with few crystal defects can be obtained.

  The scanning speed is preferably 100 mm / sec to 2000 mmsec, for example, about 1000 mm / sec. When the scanning speed is 100 mm or less, the base 10 serving as a base may melt and adversely affect the resulting silicon target 2c. When the scanning speed is 2000 mm or more, only the upper part of the silicon particles 2b is melted. In addition, the apparatus system becomes complicated to scan at a speed of 2000 mm / second or more.

  The silicon target 2c formed on the substrate 10 is peeled off from the substrate 10 and used as a silicon target for sputtering film formation. The silicon target 2c contains a dopant, like the silicon ingot 1 used as a raw material. That is, the silicon target 2c is doped P-type or N-type. The dopant concentration in the silicon target 2c is appropriately set according to the application.

  Moreover, it is preferable that the thickness of the silicon target obtained is 5-15 mm. This is because it is used as a target for sputtering film formation.

2. About the polycrystalline solar cell panel The polycrystalline solar cell panel of the present invention is formed by sputtering an amorphous silicon film on a substrate using a dopant-containing silicon target, and irradiating the formed amorphous silicon film with plasma. It is characterized in that it is heated and melted, further cooled and recrystallized to form a polycrystalline silicon film. The flow is shown in FIG. 3 and FIGS.

  First, the substrate 3 is prepared (FIG. 3A). The board | substrate 3 becomes an electrode of a solar cell. Specifically, the board | substrate 3 should just be a metal board | substrate or roll used as a back surface electrode of solar cells, such as Al, Ag, Cu, and Fe, and is not specifically limited. The substrate 3 may be a highly conductive transparent substrate, for example, an inorganic substrate containing Sn, Zn, In. If a highly conductive transparent substrate is used, a plurality of solar cells can be stacked.

  Next, an amorphous silicon film 2d is formed on the surface of the substrate 3 using a dopant-containing silicon target (FIG. 3B). The sputtered film formed using the dopant-containing silicon target is an amorphous silicon film 2d containing a dopant, like the target. That is, the amorphous silicon film 2d formed by sputtering using a P-type silicon target contains a P-type dopant; the amorphous silicon film 2d formed by sputtering using an N-type silicon target contains an N-type dopant.

  The dopant-containing silicon target used here can be a silicon target obtained from a pulverized product of the silicon ingot described above.

  Sputter film formation may be performed using a normal sputtering apparatus such as a magnetron sputtering apparatus. FIG. 4 shows an outline of the magnetron sputtering apparatus 100. The magnetron sputtering apparatus 100 includes a vacuum chamber 51; a magnetron electrode including a silicon target 2c, a water cooling jacket 61, and a magnetic circuit 60; and a substrate 3.

  The vacuum chamber 51 is provided with a gas introduction device 55, an exhaust device 56, an exhaust port 57, and a valve 58. The exhaust device 56 can apply a negative pressure to the inside of the vacuum chamber 51. The gas introduction device 55 can introduce a sputtering gas into the vacuum chamber 51. The sputtering gas is generally an inert gas such as Ar gas.

  The magnetron electrode includes a silicon target 2c, a high voltage application power source 62 connected to the silicon target 2c, and a magnetic circuit 60 disposed on the back surface (surface opposite to the surface on which the substrate 3 is disposed) of the silicon target 2c. Have. A water cooling jacket 61 is disposed between the magnetic circuit 60 and the silicon target 2c. The silicon target 2 c is attached to the packing plate 63. An earth shield 59 is disposed around the magnetron electrode.

  In addition, the substrate 3 on which the sputtered film is formed is held by the substrate holder 54, and is installed facing the silicon target 2c.

  The dopant-containing silicon target 2 c is disposed in the magnetron sputtering apparatus 100, and the substrate 3 is held by the substrate holder 54. Specific sputter deposition conditions are not particularly limited, but the internal pressure of the vacuum chamber 51 is 0.5 Pa, the power of the DC power source is 1 kW, and the electrode interval (interval between the silicon target 2 c and the substrate 3) is about 100 mm. It can be.

  The thickness t (see FIG. 3B) of the amorphous silicon film 2d formed on the substrate 3 may be changed according to the purpose in view of the texture structure and the like. The thickness t of the normal amorphous silicon film 2d is 0.1 to 0.5 μm. An amorphous silicon film should be uniformly deposited on the surface of the substrate 3 by sputtering.

The amorphous silicon film 2d is converted into a polycrystalline silicon film having a PN junction to form a silicon substrate of a solar cell panel. The flow for that can be roughly divided into the following two aspects.
First Mode) After the amorphous silicon film 2d is polycrystallized, the surface layer is doped with a dopant to form a polycrystal silicon film having a PN junction (FIG. 5).
Second Aspect) An amorphous silicon film 2e is further formed on the amorphous silicon film 2d to form an amorphous laminated film, and the amorphous laminated film is further polycrystallized to obtain a polycrystalline silicon film having a PN junction (FIG. 6). .

First Aspect The first aspect will be described with reference to FIG. The amorphous silicon film 2d (FIG. 5A) formed on the substrate 3 is irradiated with plasma to melt the amorphous silicon film 2d and further cooled to be polycrystallized to form a polycrystalline silicon film 4 (FIG. 5B). The plasma to be irradiated is preferably atmospheric pressure plasma. Irradiation of atmospheric pressure plasma can be performed using an atmospheric pressure plasma apparatus 50 similar to FIG.

  A substrate 3 on which an amorphous silicon film 2d is formed is mounted on a stage that can move in the XYZ axes of the atmospheric pressure plasma apparatus 50, and the surface of the substrate 3 is scanned from one end to the other with an atmospheric pressure plasma source for heat treatment. Do. The temperature of the atmospheric pressure plasma is generally 10000 ° C. or higher, but the temperature at the tip of the plasma injection port 22 is adjusted to be about 2000 ° C. The plasma injection port 22 is arranged at a distance of about 5 mm from the silicon powder 2 of the substrate 3. The input power is 20 kW and the plasma 23 is extruded with nitrogen gas and sprayed onto the substrate surface. The plasma 23 from the injection port 22 is irradiated to a 40 mm diameter region on the surface of the substrate 3. The amorphous silicon 2d in the region irradiated with the plasma 23 is melted.

  The temperature of the atmospheric pressure plasma 23 on the substrate surface can be arbitrarily controlled by the power of the atmospheric pressure power source, the interval between the injection port 22 and the substrate, and the like. The melting condition of the amorphous silicon 2d is adjusted by appropriately controlling the temperature of the atmospheric pressure plasma 23 on the substrate surface.

  After the amorphous silicon 2d is melted by plasma irradiation, it is further cooled by applying an inert gas (nitrogen gas or the like) to polycrystallize the molten silicon. Thereby, a polycrystalline silicon film 4 is formed on the surface of the substrate 3. At this time, when the molten amorphous silicon 2d is rapidly cooled, it becomes polycrystalline silicon having a small crystal grain size. Therefore, it is preferable to cool as rapidly as possible so that the crystal grain size becomes 0.05 μm or less.

  A trace amount of hydrogen gas may be mixed with an inert gas that extrudes plasma. By mixing a small amount of hydrogen, it is possible to remove the oxide film on the surface of the amorphous silicon 2d and to obtain the polycrystalline silicon film 4 with few crystal defects.

  The scanning speed of the plasma irradiation is preferably 100 mm / second to 2000 mm / second, for example, about 1000 mm / second. If the scanning speed is 100 mm / second or less, the substrate 3 as a base may melt and adversely affect the resulting polycrystalline silicon film 4. If the scanning speed is 2000 mm / second or more, only the upper part of the amorphous silicon 2d is melted. Further, in order to scan at a speed of 2000 mm / second or more, the apparatus system becomes complicated.

  As described above, since the silicon film formed on the substrate 3 is the amorphous silicon film 2d, the silicon film can be melted by atmospheric pressure plasma. By using atmospheric pressure plasma, the amorphous silicon 2d disposed on the substrate 3 having a large area can be efficiently melted and recrystallized. On the other hand, it is usually difficult to melt bulk silicon with atmospheric pressure plasma.

Next, the texture structure 5 is formed by processing the surface of the polycrystalline silicon film 4 into an uneven shape (FIG. 5C). Generally, the incident surface of the silicon film of the solar cell is made the texture structure 5 to suppress reflection at the incident surface. The processing means for the surface of the polycrystalline silicon film 4 is not particularly limited, and it is treated with acid or alkali (KOH or the like), or gas plasma with chlorine trifluoride gas (ClF ₃ ) or sulfur hexafluoride (SF ₆ ). Or may be processed. The specific texture structure 5 is not particularly limited, and may be a known structure.

  A dopant is implanted into the surface layer 6 of the polycrystalline silicon film 4 having the texture structure 5 (FIG. 5D). Specifically, when the polycrystalline silicon film 4 contains a P-type dopant, an N-type dopant is implanted into the surface layer 6 of the polycrystalline silicon film 4; the polycrystalline silicon film 4 contains an N-type dopant. In this case, a P-type dopant is implanted into the surface layer 6 of the polycrystalline silicon film 4.

The dopant is preferably implanted using plasma. In order to inject phosphorus or arsenic, which are N-type dopants, plasma is applied to the polycrystalline silicon film 4 in the presence of a phosphorus element-containing gas (such as PH- ₃ ) or an arsenic element-containing gas (AsH ₃ ). Good. In order to plasma-inject boron, which is a P-type dopant, the polycrystalline silicon film 4 may be irradiated with plasma in the presence of a boron element-containing gas (BH ₃ ).

  After the dopant is implanted, the dopant is activated by irradiating the surface layer 6 of the polycrystalline silicon film 4 with a lamp or the like. Thereby, a polycrystalline silicon film 4 having a PN junction is formed.

  Further, an insulating film 7 is stacked on the polycrystalline silicon film 4 (FIG. 5E). The insulating film 7 may be a silicon nitride film or the like. By laminating the insulating film 7, reflection of incident light is suppressed and deterioration of electrical characteristics is prevented. Further, a part of the insulating film 7 is etched to form the electrode 8 in the line-shaped etched portion (FIG. 5E). The material of the electrode 8 is, for example, silver.

Second Mode A second mode will be described with reference to FIG. Another amorphous silicon film 2e is laminated on the amorphous silicon film 2d (FIG. 6A) formed on the substrate 3. The amorphous silicon film 2e contains a dopant. Specifically, when the amorphous silicon film 2d contains a P-type dopant, the amorphous silicon film 2e contains an N-type dopant; when the amorphous silicon film 2d contains an N-type dopant, The amorphous silicon film 2e contains a P-type dopant.

  As with the amorphous silicon film 2d, the amorphous silicon film 2e is preferably formed by sputtering film formation using a dopant-containing silicon target. If a P-type silicon target is used, a P-type dopant-containing amorphous silicon film 2e is formed; if an N-type silicon target is used, an N-type dopant-containing amorphous silicon film 2e is formed. The dopant-containing silicon target for sputtering the amorphous silicon film 2e is also preferably obtained from a pulverized silicon ingot as described above.

  The thickness of the amorphous silicon film 2e is preferably 0.5 to 50 μm. Moreover, it is preferable that the standard of the thickness of the amorphous silicon film 2e is 2 to 10% with respect to the thickness of the amorphous silicon film 2d. By optimizing the thickness of both, power generation efficiency can be increased.

  The laminated film of the amorphous silicon film 2d and the amorphous silicon film 2e is melted by irradiating with plasma, and further cooled to be polycrystallized to form the polycrystal silicon film 4 (FIG. 6C). The plasma to be irradiated is preferably atmospheric pressure plasma.

  The apparatus and method for irradiating the atmospheric pressure plasma may be the same as in the case of obtaining the polycrystalline silicon film 4 in FIG. 5B.

  Next, the texture structure 5 is formed by processing the surface of the polycrystalline silicon film 4 into an uneven shape (FIG. 6D). The formation of the texture structure 5 may be the same as the formation of the texture structure 5 in FIG. 5C.

  Further, an insulating film 7 is formed on the polycrystalline silicon film 4, and an electrode 8 is formed (FIG. 6E). The insulating film 7 and the electrode 8 are the same as those in FIG. 5E.

Other Forms In the first and second aspects, the amorphous silicon film 2d is formed on the substrate 3. In this embodiment (another embodiment), a silicon powder 2b containing a dopant is disposed on the substrate 3; a dopant-containing amorphous silicon film 2d is formed on the silicon powder 2b; The polycrystalline silicon film 4 having a PN junction is obtained by polycrystallizing the powder 2b and the amorphous silicon film 2d (see FIG. 7).

  This embodiment (another embodiment) will be described with reference to FIG. First, silicon powder 2b is applied to the substrate 3 (FIG. 7A). The substrate 3 is the same as the substrate 3 in FIG. 3A. The silicon powder 2b is a silicon powder 2b obtained by pulverizing a dopant-containing silicon ingot (see FIG. 1B), and contains a P-type dopant or an N-type dopant.

  The silicon powder 2b is applied by a) applying a dry silicon powder with a squeegee, or b) applying an ink obtained by dispersing the silicon powder 2b in a solvent by spin coating, die coating, inkjet, dispenser or the like. Also good. The ink can be obtained by dispersing silicon powder in alcohol or the like. An ink containing silicon powder can be obtained by referring to, for example, JP-A-2004-318165.

The amount of the silicon powder 2b applied to the substrate 3 needs to be accurately adjusted, and specifically, it is preferably set to about ² to 112 g / cm ² . However, the coating film surface of the silicon powder 2b applied to the substrate 3 may have some unevenness. As will be described later, the applied silicon powder 2b is melted by plasma, so that the coating film is smoothed.

  Next, an amorphous silicon film 2d is formed and laminated on the applied silicon powder 2b (FIG. 7B). The amorphous silicon film 2d contains a dopant. When the silicon powder 2b contains a P-type dopant, the amorphous silicon film 2d contains an N-type dopant; when the silicon powder 2b contains an N-type dopant, the amorphous silicon film 2d becomes P Contains type dopants.

  The silicon amorphous film 2d is formed using a sputtering apparatus or a CVD apparatus; however, it is preferable that the silicon amorphous film 2d is formed using the dopant-containing silicon target 2c described above. By forming the silicon amorphous film 2d, a part of the silicon powder 2b (amorphous silicon film 2d side) may be amorphous.

  The thickness of the amorphous silicon film 2d laminated on the silicon powder 2b is not particularly limited, but may be 0.1 to 0.5 μm.

  Next, the silicon powder 2b and the silicon amorphous film 2d on the substrate 3 are melted by atmospheric pressure plasma and further cooled to form the polycrystalline silicon film 4 (see FIG. 7C). Irradiation with atmospheric pressure plasma may be performed by the apparatus shown in FIG. The method is also the same as that in the second embodiment when the laminated film of the amorphous silicon film 2d and the amorphous silicon film 2e is a polycrystalline silicon film (see FIG. 6C).

  The polycrystalline silicon film 4 is formed with a PN junction, and the thickness of the polycrystalline silicon film 4 is preferably 0.5 to 50 μm.

  Next, the texture structure 5 is formed by processing the surface of the polycrystalline silicon film 4 into an uneven shape (FIG. 7D). The formation of the texture structure 5 may be the same as the formation of the texture structure 5 in FIG. 5C. The surface layer 6 of the polycrystalline silicon film 4 is activated.

  Further, an insulating film 7 is formed on the polycrystalline silicon film 4, and an electrode 8 is formed (FIG. 7E). The insulating film 7 and the electrode 8 are the same as those in FIG. 5E (FIG. 7E).

[Experimental Example 1]
A boron-containing amorphous silicon film 2d was formed by sputtering on a substrate (material: aluminum, size: 370 mm (X axis) × 470 mm (Y axis)) using a boron-containing silicon target (FIG. 5A). The thickness of the amorphous silicon film 2d was 50 μm.

  Next, plasma is irradiated from one end of the substrate to the other end while scanning in the X-axis direction with an atmospheric pressure plasma apparatus as shown in FIG. 2, and the amorphous silicon 2d is melted and recrystallized to obtain polycrystalline silicon. It was set as the film | membrane 4 (FIG. 5B). The plasma irradiation area was 40 mm in diameter. The inert gas that pushes out the plasma was nitrogen gas containing a trace amount of hydrogen gas. When the scanning from one end to the other end was completed, the plasma was irradiated while being shifted by 40 mm in the Y-axis direction and scanning in the X-axis direction again. By repeating this, all of the amorphous silicon 2d disposed on the substrate was recrystallized in a band shape to obtain a substantially homogeneous polycrystalline silicon film. The thickness of the polycrystalline silicon film 4 was about 50 μm.

  Next, the surface of the polycrystalline silicon film 4 was processed into a concavo-convex shape (textured) (FIG. 5C). Processing of the surface of the polycrystalline silicon film 4 may be performed by wet etching with an acid or alkali (KOH or the like) solution, or by gas plasma using chlorine trifluoride gas (ClF3) or sulfur hexafluoride (SF6). Etching may be performed.

Next, phosphorus was doped on the surface of the polycrystalline silicon film 4 using plasma (FIG. 5D). Doping is carried out by introducing PH ₃ gas (0.5% He dilution) into a 20 SCCM chamber under a pressure environment of 10 Pa; doping treatment is performed at a power of 200 W for 30 seconds using a high frequency discharge of 13.56 MHz. went. The doped polycrystalline silicon film 4 was irradiated with a lamp to activate the impurities.

  Further, an insulating film 7 (silicon nitride film) was formed by sputtering for the purpose of preventing reflection and preventing deterioration of electrical characteristics at the crystal edge (FIG. 5E). Further, a part of the insulating film 7 was etched to form a line-shaped silver electrode 8 in the etched portion.

In this way, a solar cell having an open circuit voltage of 0.6 V (10 cm ² conversion) was obtained. This data is comparable to that of currently available crystal solar cells.

  In Experimental Example 1, a boron-containing amorphous silicon film 2d was formed, polycrystallized, and phosphorus was doped to form a PN junction. On the other hand, a similar result can be obtained by forming an arsenic or phosphorus-containing amorphous silicon film, polycrystallizing it, and doping a P-type dopant such as boron to form a PN junction.

[Reference Example 1]
Boron-containing amorphous silicon 2d was sputter-deposited on a substrate (material: aluminum, size: 370 mm (X axis) × 470 mm (Y axis)) using a boron-containing silicon target (FIG. 6A). The thickness of the amorphous silicon 2d was 50 μm.

  An arsenic-containing amorphous silicon film 2e was formed by sputtering on the boron-containing amorphous silicon 2d to form a laminated film (FIG. 6B). The thickness of the arsenic-containing amorphous silicon film 2e was 2 μm.

  Next, with an atmospheric pressure plasma apparatus as shown in FIG. 2, while scanning in the X-axis direction, plasma is irradiated from one end of the substrate to the other end to melt and recrystallize amorphous silicon 2d and 2e. A crystalline silicon film 4 was obtained (FIG. 6C). The plasma irradiation area was 40 mm in diameter. The inert gas that pushes out the plasma was nitrogen gas containing a trace amount of hydrogen gas. When the scanning from one end to the other end was completed, the plasma was irradiated while being shifted by 40 mm in the Y-axis direction and scanning in the X-axis direction again. By repeating this, all of the amorphous silicon 2d and 2e arranged on the substrate were recrystallized in a band shape to obtain a substantially homogeneous polycrystalline silicon film.

  Next, the surface of the polycrystalline silicon film 4 was processed into an uneven shape (textured) (FIG. 6D).

  Further, an insulating film 7 (silicon nitride film) was formed by sputtering for the purpose of preventing reflection and preventing deterioration of electrical characteristics at the crystal edge (FIG. 6E). Further, a part of the insulating film 7 was etched to form a line-shaped silver electrode 8 in the etched portion (FIG. 6E).

In this way, a solar cell with an open circuit voltage of 0.6 V (converted to 10 cm ² ) was obtained. This is data comparable to that of currently available crystal solar cells.

  In Reference Example 1, after forming the boron-containing amorphous silicon film 2d, the arsenic-containing amorphous silicon film 2e was laminated and a PN junction was formed by gas plasma. On the other hand, the same result can be obtained by forming the arsenic-containing amorphous silicon film 2d and then laminating the boron-containing amorphous silicon film 2e and forming a PN junction by gas plasma.

[Reference Example 2]
A silicon powder 2b having a particle diameter of about 1 μm was applied to a substrate (material: aluminum, size: 370 mm (X axis) × 470 mm (Y axis)) (FIG. 7A). Since the silicon powder 2b is obtained by pulverizing a boron-containing silicon ingot, it is P-type doped. The silicon powder 2b was applied with a squeegee to form a coating film having a thickness of about 30 μm.

  Thereafter, a silicon amorphous film 2d was formed on the silicon powder 2b using a phosphorus-containing silicon target (FIG. 7B). The thickness of the silicon amorphous film 2d was 2 μm.

  With an atmospheric pressure plasma apparatus as shown in FIG. 2, while irradiating plasma from one end of the substrate to the other end while scanning in the X-axis direction, the silicon powder and the silicon amorphous film are melted and recrystallized to obtain polycrystalline silicon. Film 4 was obtained (FIG. 7C). The plasma irradiation area was 40 mm in diameter. The inert gas that pushes out the plasma was nitrogen gas containing a trace amount of hydrogen gas. When the scanning from one end to the other end was completed, the plasma was irradiated while being shifted by 40 mm in the Y-axis direction and scanning in the X-axis direction again. By repeating this, all of the silicon powder and the silicon amorphous film disposed on the substrate were recrystallized into a band shape to obtain a substantially homogeneous polycrystalline silicon film. The thickness of the polycrystalline silicon film was 15 μm.

  Next, the surface layer 6 of the formed polycrystalline silicon film 4 was processed into a concavo-convex shape (textured). (FIG. 7D). Processing of the surface of the polycrystalline silicon film 4 may be performed by wet etching with an acid or alkali (KOH or the like) solution, or by gas plasma using chlorine trifluoride gas (ClF3) or sulfur hexafluoride (SF6). Etching may be performed.

  Further, an insulating film 7 (silicon nitride film) was formed by sputtering for the purpose of preventing reflection and preventing deterioration of electrical characteristics at the crystal edge (FIG. 7E). Further, a part of the insulating film 7 was etched to form a line-shaped silver electrode 8 in the etched portion (FIG. 7E).

In this way, a solar cell with an open circuit voltage of 0.6 V (converted to 10 cm ² ) was obtained. This data is comparable to that of currently available crystal solar cells.

  In Reference Example 2, the boron-containing silicon powder 2b was applied to the substrate 3, and a phosphorus-containing silicon amorphous film 2d was further formed as the polycrystalline silicon film 4. On the other hand, the same effect can be obtained by applying phosphorus (P) or arsenic (As) -containing silicon powder to the substrate 3 to form a boron-containing silicon amorphous film 2d and using them as the polycrystalline silicon film 4. .

  According to the present invention, a solar cell panel having a large area can be provided inexpensively and efficiently. The silicon sputter target provided by the present invention can be used as a silicon raw material for a crystalline solar cell. Moreover, according to this invention, a solar cell panel of a large area can be provided cheaply and efficiently.

DESCRIPTION OF SYMBOLS 1 Silicon ingot 2a Silicon coarse powder 2b Silicon powder 2c Silicon target 2d Amorphous silicon film 2e Amorphous silicon film 3 Substrate 4 Polycrystalline silicon film 5 Texture structure 6 Surface layer of polycrystalline silicon film 7 Insulating film 8 Electrode 10 Base 20 Cathode 21 Anode 22 Plasma injection port 23 Plasma 30 Silicon ingot 31 Wire 40 Silicon anode 41 Arc discharge 42 Silicon particle 43 Argon gas 44 Transport tube 45 Support substrate 46 High temperature plasma 47 Halogen lamp 48 Separation chamber 49 Polycrystalline silicon film 50 Atmospheric pressure plasma device 51 Vacuum chamber 54 Substrate holder 55 Gas introduction device 56 Exhaust device 57 Exhaust port 58 Valve 59 Earth shield 60 Magnetic circuit 61 Water cooling jacket 62 High voltage application power source 63 King plate 100 magnetron sputtering apparatus

Claims (6)

Preparing a silicon target containing a P-type or N-type dopant; and
Using a silicon target containing the P-type or N-type dopant, a step B of forming a P-type or N-type amorphous silicon film on the substrate surface by sputtering;
A step C of forming a P-type or N-type polycrystalline silicon film by scanning and melting the P-type or N-type amorphous silicon film, followed by recrystallization;
A PN junction is formed by exposing the P-type polycrystalline silicon film formed in the step C to plasma with a gas containing an N-type dopant, or the N-type polycrystalline silicon film formed in the step C. A step D of forming a PN junction by exposure to plasma with a gas containing a P-type dopant;
A method for producing a polycrystalline solar cell panel, comprising:   The method for manufacturing a polycrystalline solar cell panel according to claim 1, wherein the substrate includes any one of Al, Ag, Cu, Sn, Zn, In, and Fe.   The method for manufacturing a polycrystalline solar cell panel according to claim 1, wherein the plasma is atmospheric pressure plasma.   The method for manufacturing a polycrystalline solar cell panel according to any one of claims 1 to 3, wherein the scanning speed is 100 mm / second or more and 2000 mm / second or less.   In the step C, after the P-type or N-type amorphous silicon film is melted by plasma irradiation, an inert gas is supplied to melt the P-type or N-type amorphous silicon film to be polycrystallized. Item 5. The method for producing a polycrystalline solar cell panel according to any one of Items 1 to 4.   The polycrystalline solar cell panel according to any one of claims 1 to 4, wherein in the step C, plasma irradiation is performed while extruding the generated plasma with a mixed gas obtained by mixing hydrogen gas with an inert gas. Production method.

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